Like @lloydg posted, you can create a funnel where each step is a levelComplete event and the value passed would correspond to the level number in your game. Ex. Custom Event: levelComplete, Parameter: level =1
You would also pass another parameter, number of times accessed, with the custom event so you would be able to view the average number of times a user accessed a particular level. You would then view this information in the Funnel Analyzer page by changing the Drilldown Type to Parameters Overview. In the example I have attached the ‘points’ column would be replaced with your number of times accessed parameter.
Just to clarify, send a custom event at the end of each level with the level number and the number of times that level was accessed, and build a funnel that will be populated by that custom event.
Please let me know if you have any other questions.